Tidepools in Dead Man’s Cove show large fluctuations in carbonate chemistry during the low tide in comparison to Haro Stait water

Abstract:

During the low tide, tidepools are under different physio-chemical conditions than the
coastal waters. This includes the carbonate chemistry, which is especially pertinent to
study due to the threat of ocean acidification on carbonate chemistry. We examined the
fluctuation in DIC, total alkalinity, pH, temperature, dissolved oxygen, and salinity in
two tide pools in Dead Man’s Cove, San Juan Island, WA over the course of the low tide.
To better understand the relative contributions of photosynthesizers and respirers to
changes in carbonate chemistry, we added Ulva to one pool on the second day, and
Mytilus trossulus on the third day. During the low tide, tidepools saw a decrease in DIC
and alkalinity, and an increase in pH, temperature, and dissolved oxygen. There is
evidence of a small signal of decrease in DIC due to Ulva addition and increased DIC due
to Mytilus addition. Tidepools experience huge swings in carbonate chemistry that
suggests an ability of the organisms that inhabit the pools to cope with large changes in
pH over the course of the day.